Ms. Palin was the last prominent Republican who had yet to confirm her attendance, and some of her supporters had held out hope that she would agree to deliver a speech at the event Feb. 10-12 in Washington. But organizers of the event confirmed Thursday that she would not attend, marking the third year in a row that she has opted out of the conference that features thousands of conservative activists.

Ms. Palin, the former Alaska governor, had been asked to give the closing address at the conference — a prominent speaking position that last year was given to Glenn Beck of Fox News — but she did not respond to the invitation in time, so the position was offered to someone else. But late Wednesday, Ms. Palin sent word to organizers that she had a scheduling conflict and would not attend any portion of the conference.

The decision to skip the Conservative Political Action Conference comes as Republican activists are clamoring to know whether Ms. Palin is serious about running for president. She has given far fewer signs about her intentions than other potential rivals. Yet the tea leaves are difficult to read because Ms. Palin has had a contentious relationship with the conference.

In 2008, she dropped out of the event only days before it was to begin. In 2009, she accepted an invitation but ultimately declined, saying she was busy with her duties as governor of Alaska. And in 2010, she also declined an invitation and raised questions about the event organizers, the American Conservative Union, and its chairman, David Keene.

Even though Ms. Palin will not be in attendance, her political action committee, SarahPAC, is hosting a reception on the opening night of the conference. She is not the only Republican to take a pass on the event. Some leading conservatives have voiced their disagreement that a gay conservative group, GOProud, is one of the sponsors. Senator Jim DeMint, Republican of South Carolina, and the Family Research Council, a prominent conservative organization, have declined to participate.

The event also features a straw poll, where attendees choose who they believe would make the strongest Republican presidential candidate to challenge President Obama.

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